Failure Reason 2: Inadequate Pinning System

What happens here

The second issue discussed is the inadequate pinning system of many cheap blocks. Instead of using pins that drive down and through the blocks for a secure mechanical connection, these blocks rely solely on a small lip on the back to connect one block to the one below it. This lip is insufficient. As soon as ground movement, freeze-thaw cycles, or erosion occur, this weak connection gives way, causing the blocks to push up and over, losing all connection.

Goal: Understand how weak lip connections cause retaining wall instability.